Reversal of pre-existing NGFR-driven tumor and immune therapy resistance

Melanomas can switch to a dedifferentiated cell state upon exposure to cytotoxic T cells. However, it is unclear whether such tumor cells pre-exist in patients and whether they can be resensitized to immunotherapy. Here, we chronically expose (patient-derived) melanoma cell lines to differentiation antigen-specific cytotoxic T cells and observe strong enrichment of a pre-existing NGFRhi population. These fractions are refractory also to T cells recognizing non-differentiation antigens, as well as to BRAF + MEK inhibitors. NGFRhi cells induce the neurotrophic factor BDNF, which contributes to T cell resistance, as does NGFR. In melanoma patients, a tumor-intrinsic NGFR signature predicts anti-PD-1 therapy resistance, and NGFRhi tumor fractions are associated with immune exclusion. Lastly, pharmacologic NGFR inhibition restores tumor sensitivity to T cell attack in vitro and in melanoma xenografts. These findings demonstrate the existence of a stable and pre-existing NGFRhi multitherapy-refractory melanoma subpopulation, which ought to be eliminated to revert intrinsic resistance to immunotherapeutic intervention

Augmenting Immunotherapy Impact by Lowering Tumor TNF Cytotoxicity Threshold

New opportunities are needed to increase immune checkpoint blockade (ICB) impact for cancer patients. A genome-wide CRISPR/Cas9 screen uncovered several hits in the TNF pathway sensitizing tumor cells to T cell elimination. TNF antitumor activity was generally limited in tumors at baseline and in ICB non-responders, correlating with its low abundance. Selective inactivation of TNF signaling lowered melanoma and lung cancer thresholds to low TNF levels, thereby increasing tumor susceptibility to T cell attack and augmenting benefit from anti-PD-1 treatment